2002 silverado 1500 4x4 5.3 l engine codes p0101 p0300

richurbs · **Joined:** Sun Nov 23, 2008 11:25 am **Posts:** 1

i have a 02 chevy silverado 5.3 liter 83000 mile replaced maf sensor o2 sensors before cat still getting p0101 and p0300 codes can anyone help me

Sponsored Links · **Joined:** 29 Jun 2004 08:12 pm **Posts:** N/A

asecmt · **Posted:** Sun Nov 23, 2008 11:34 am

O2 sensors have nothing to do with either code.. Usually when you get both of these codes on this vehicle one of the convertors is clogged. You need a scan tool with live data and if cylinders 1 3 5 7 show misfires or cylinders 2 4 6 8 show misfires then this a good indication that this is the problem.

leclouxa · **Joined:** Tue Nov 25, 2008 1:32 pm **Posts:** 6

hey i have the same problem with me truck. the other day when it was about 10 or 15 degrees out my truck wouldn't wanna start right away but then it did and the check engine light came on but it ran just fine and idled just fine just didnt want to start right away took a lil longer , so i pluged in my dads scan tool and i got p0300 (mis fire) so we cleared the code and then it came on again, so this time i took it to my buddy and he used his scan tool. same code again but then we took reading and i hade more misfires on 1,3,5 and 7 and very little on 2,4,6, and 8. but then 7 and 8 had the most

where do i start?? could it be injector, Cats, Maf, coils?? jst put in plugs and wires also and tested them wit a coil tester and they all tested just fine. so before i start stickin in money where should i start?

dnold · **Joined:** Thu Nov 13, 2008 9:49 pm **Posts:** 35

Misfire codes on a 5.3 on a cold morning is more than likely leaking intake manifold gaskets. Last year I had a run of 6 trucks during a cold snap of 0 deg and I ran our dealership out of gaskets. Very common problem. The intake can also warp, take a straight edge to it and see how bad it is.

asecmt · **Posted:** Sat Nov 29, 2008 5:38 am

Intake gaskets are common but usually set P0171 P0174 and P0300.

leclouxa · **Joined:** Tue Nov 25, 2008 1:32 pm **Posts:** 6

"You need a scan tool with live data and if cylinders 1 3 5 7 show misfires or cylinders 2 4 6 8 show misfires then this a good indication that this is the problem.
O2 sensors have nothing to do with either code.. Usually when you get both of these codes on this vehicle one of the convertors is clogged." what do you mean by live data?

how would i be sure if its my intake gasket and nothing else?? there ne way i can check?? would back pressure have ne thing to do with it?

asecmt · **Posted:** Tue Dec 02, 2008 7:00 pm

you could remove the o2 sensors before the cat and check back pressure. If it is the intake gaskets it will run rough when cold and then smooth out after a couple mins of running.

leclouxa · **Joined:** Tue Nov 25, 2008 1:32 pm **Posts:** 6

: If it is the intake gaskets it will run rough when cold and then smooth out after a couple mins of running."
Its only runs rough when it sits over night in 15 or below weather but i dont have to give itgas or ne thing like that it turns over but takes a lil longer to fire

asecmt · **Posted:** Wed Dec 03, 2008 5:51 pm

sounds like intake gaskets to me.. It would be better if you had a scan tool so you you can look at fuel trim numbers and that would say for sure. GM has updated the intake gaskets for this problem so be sure to get them from the dealer.

dnold · **Joined:** Thu Nov 13, 2008 9:49 pm **Posts:** 35

Def. intake gaskets. I take a spray can of carb and choke cleaner and give the intake gaskets a small spray when it is running rough. If they are leaking it will smooth out and idle higher because it is a vacuum leak that you richen up with the carb cleaner. Use only OEM gaskets.

leclouxa · **Joined:** Tue Nov 25, 2008 1:32 pm **Posts:** 6

ok sorry guys my bad i ment to say it doesn't run rough. it only starts hard when its cold out below 15 degrees or ten. but then after that it clears up. and i have access to a scan tool my buddy has one and it shows that the left side has alot of miss firing compared to the right side bank but 7 and 8 show the most out of all of them. and like i said i havge no problem it runs and drives fine. no weird engine noises or ne thin like that no losses of power either

leclouxa · **Joined:** Tue Nov 25, 2008 1:32 pm **Posts:** 6

and i have also used a spark plug tester into each coil and plug and it flashes like it is suppose to.

so that would indacate that there is plenty of spark and guessing it wouldnt be a electrical problem. right? :?:

dnold · **Joined:** Thu Nov 13, 2008 9:49 pm **Posts:** 35

Does it show missfires on more than just cylinders 7 and 8? Check fuel pressure and check to make sure pressure holds with engine off. Still could and probably is intake gaskets.

10gunman · **Joined:** Tue Dec 09, 2008 2:50 pm **Posts:** 10

hello guys I have a 99 chevy silverado with the same issue it started about 4 days ago with a po354 and today i have replaced the spark plugs. after that went for a test drive then when i got home I was going to replace the coil on cyl #4 since po354 suggested it, now it's giving me a po300 code and then now it doesn't start no click or anything now I'm thinking the crank position sensor cause it doesn't do anything when I turn the key. HELP ME! :?:

10gunman · **Joined:** Tue Dec 09, 2008 2:50 pm **Posts:** 10

oh before i forget the mil light started flashing when I went for the test drive. i was reading the manual and it said that if the mil is flashing this indicates that a catalyst misfire has occurred I don't know what that mens maybe that the catalitic converter is being damaged?

2002 silverado 1500 4x4 5.3 l engine codes p0101 p0300

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